Cast Singularity Rupture by paying its mana cost, destroying all creatures and causing any number of opponents to mill a number of cards equal to half their library, rounded down, times two due to Bruvac. You can also have yourself mill half your library, if desired.

Infinite mill

Near-infinite self-mill

Bruvac the Grandiloquent

Singularity Rupture

Cast Singularity Rupture with kicker by paying {4}{U}{U}, causing each opponent to mill half their library, rounded up.
Activate Riverchurn Monument's exhaust ability by paying {2}{U}{U} and tapping it, causing each opponent to mill the remainder of their library.

Combos with "Singularity Rupture"